A Reclaimed Wastewater Allocation Optimization Model for Agricultural Irrigation

Abstract

Climate change, pollution, civil conflicts, political instability, and a high rate of population growth all contribute to water shortages in Iraq which are predicted to increase in the future. Due to the importance of agriculture in Iraq which forms more than 75 percent of total demand, a sustainable agricultural water allocation scheme is necessary to find practical and applicable water conservation measures that helps mitigate the impact of potential droughts and water shortages. An agricultural irrigation reclaimed wastewater allocation optimization model was developed to optimally allocate crops and reclaimed wastewater (RW) on cultivated farmlands in order to maximize the net benefit. The optimization model is formulated using mixed-integer nonlinear programming (MINLP) solved by the branch and reduce optimization navigator (BARON) in the general algebraic mathematical solver (GAMS). The model maximizes the net farm income to determine the cultivated crop assigned to each farmland using three types of reclaimed wastewater (RW); tertiary treated wastewater; secondary treated wastewater; and primary treated wastewater. Constraints in the optimization model include: (1) reclaimed wastewater availability constraints and (2) irrigated farmlands constraints. The optimization model has been applied to 7045 hectares of farms located in the Alrustumia district to the south east of Baghdad, Iraq with 5.5 × 105 m3/d of treated wastewater. The use of tertiary treated wastewater provided the greatest net benefit under most scenarios evaluated while primary effluent provided the lowest net benefit as only low value crops could be cultivated.

Optimization Model for Agricultural Reclaimed Water Allocation Using Mixed-Integer Nonlinear Programming

“…Proportional sharing ensures that water is allocated to all provinces that use the Tigris and Euphrates Rivers as water sources for irrigation. A mixed integer non-linear programming water allocation optimization model solved using the branch and reduce optimization navigator (BARON) was developed by Aljanabi, et al [10] for water allocation in Iraq. The model compares the maximized net benefit from the use of reclaimed water type A, reclaimed water type B, and reclaimed water type C for cultivating different types of crops on 106 agricultural farms.…”

Tuning ANN Hyperparameters by CPSOCGSA, MPA, and SMA for Short-Term SPI Drought Forecasting

“…As a result, many storage dams have been built along the paths of these rivers in Iraq [14]. These rivers had severe water shortages from 2009 to 2014, which are predicted to increase due to climate change, leading to a rise in upstream water consumption (i.e., Turkey and Iran) [14,15]. Climate change has significant effects in Iraq, such as decreasing rainfall and increasing temperatures [16].…”